Wash the potatoes and cook for about 20 minutes. Quench and peel. Clean, wash and cut leek into rings. Steam in 3/8 l boiling water covered with broth for 5-6 minutes. Drain and collect the stock. Wash, dry and dice the smoked pork loin.
Heat 1 tablespoon of fat in a saucepan. Brown the smoked pork loin on all sides, remove. Heat 3 tbsp. fat in the frying fat. Sauté the flour in it. Stir in leek stock, milk and marjoram. Bring to the boil and simmer for about 5 minutes. Season with mustard, pepper and possibly salt
Fill potatoes, leek and cured pork loin into a greased casserole dish (approx. 30 cm long). Pour sauce over it. Grate cheese, sprinkle over it. Bake in the preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/gas: level 3) for 25-30 minutes, garnish